After a long and exceptionally negative campaign, Americans by the millions voted on Tuesday for their next president as opinion polls showed Democrat Hillary Clinton with a narrow lead over Republican Donald Trump. In a battle that focused on the character of the candidates, Clinton, 69, a former U.S. first lady, senator and secretary of state, and Trump, 70, a New York businessman, made final, fervent appeals to voters late on Monday to turn out at the polls.

Clinton led Trump, by 44 percent to 39 percent, in the last Reuters/Ipsos national tracking poll before Election Day. A Reuters/Ipsos States of the Nation poll gave Clinton a 90 percent chance of defeating Trump and said she was on track to win 303 Electoral College votes, with 270 needed for election.

Financial markets were closely watching the election. U.S. stocks slipped in cautious trading on Tuesday morning after they soared on Monday on belief by investors that Clinton was more likely to win the White House. The dollar rose against the safe-haven Japanese yen and Swiss franc on Tuesday, but was overall little moved.

Polls begin to close at 7 p.m. Eastern Time, with the first meaningful results due about an hour later. U.S. television networks called the winner of the 2008 and 2012 presidential elections at 11 p.m. or shortly after. Victory in U.S. presidential elections is earned not by the popular vote, but by an Electoral College system that awards the White House on the basis of state-by-state wins, meaning a handful of states where the race is close assume an outsized importance.

The marathon U.S. election campaign, which kicked off in early 2015, has been unusually negative, with each candidate accusing the other of lacking the character and judgment to be president. Majorities of voters in opinion polls have viewed both candidates unfavorably.

Mary Wheeler, 94, held her nose when asked which candidate she was supporting as she stood in line to vote at the Coliseum ballroom in St. Petersburg, Florida, an important presidential battleground state.

"I always vote Republican, so I guess I'll do that," Wheeler said. "He can make a fool of himself but I think he may be able to straighten things out a little bit," she said of Trump.

In Cleveland, Timothy Sommerfelt, 30, said he voted for Clinton at the Joseph M. Gallagher School polling site. "I don't think Donald Trump would do a good job," Sommerfelt said, adding that his vote "is a vote against Donald, obviously."

FIRST WOMAN PRESIDENT?

Trump and Clinton were seeking to become the 45th president of the United States and the successor to Democrat Barack Obama, who served two four-year terms in the White House and is barred by the U.S. Constitution from seeking another term.

Clinton, who is aiming to become the first woman U.S. president, cast her ballot at an elementary school near her home in Chappaqua, New York early on Tuesday morning. "It is the most humbling feeling. I know how much responsibility goes with this. So many people are counting on the outcome of this election, what it means for our country. And I'll do the very best I can if I'm fortunate enough to win today," Clinton said.

Trump, a former reality TV star, received a mixture of cheers and jeers as he arrived to vote at a school in Manhattan. He said voting so far looked good for him. "It's very good generally speaking. It's a great feeling." Asked if he would concede if the TV networks declared Clinton the winner, he answered, "Well, we'll see what happens." Trump, who has argued that the political system is rigged against him, previously has said he might not accept the election results if he loses.

More than 40 million voters cast ballots before Election Day in early voting in many states.

Clinton spent eight years in the White House as first lady from 1993 to 2001 before serving as a senator and as Obama's secretary of state.

Trump, launching his first bid for elected office after decades as a public figure, has positioned himself as an agent of change, vowing to crack down on illegal immigration and end trade deals he says are harming U.S. workers. He was expected to draw support heavily from white voters without college degrees.

Clinton was likely to draw support from college-educated voters and Hispanic and black voters. She has vowed to largely continue the policies of Obama and to overcome income inequality among Americans, with a divide between the rich and poor.

Major bookmakers and online exchanges were confident she would win. Online political stock market PredictIt put her chances on Tuesday of capturing the White House at 80 percent, down 2 percentage points from Monday.

Trump advisers say the level of his support is not apparent in opinion polls and that they believe the real estate developer is in position for an upset victory along the lines of the "Brexit" vote in June to pull Britain from the European Union.

MUST-WIN STATES

An early indicator of who might prevail could come in North Carolina and Florida, two must-win states for Trump that were the subject of frantic last-minute efforts by both candidates. Races in both those states were shifting from favoring Clinton to being too close to call, according to opinion polls. Democrats also are seeking to break the Republican lock on control of the U.S. Congress.

A strong turnout of voters for Clinton could jeopardize Republican control of the Senate, as voters choose 34 senators of the 100-member chamber on Tuesday. Democrats needed a net gain of five seats to win control. All 435 seats in the House of Representatives were being contested. The House was expected to remain in Republican hands.

Trump reveled in the drama of the negative presidential campaign and seized the spotlight time and again with provocative comments about Muslims and women, attacks against the Republican establishment and bellicose promises to build a wall along the U.S. southern border with Mexico to stem illegal immigration.

But the spotlight was not always kind to Trump. The release in October of a 2005 video in which he boasted about groping women damaged his campaign and left him on the defensive for critical weeks.

Clinton, with a long reputation for secrecy, sustained damaging blows from her handling of classified information as the country's top diplomat. FBI Director James Comey shook up the race and slowed Clinton's momentum with an Oct. 28 announcement the agency was reviewing newly discovered emails perhaps related to her email practices. But on Sunday, Comey ruled out criminal wrongdoing by Clinton.

The final week of campaigning was a grinding series of get-out-the-vote rallies across battleground states where the election is likely to be decided. "Today is our Independence Day," Trump said during an appearance on Monday in Grand Rapids, Michigan, accompanied by vice presidential running mate Mike Pence, the governor of Indiana. "Today the American working class is going to strike back, finally," Trump said.

Clinton, whose running mate is U.S. Senator Tim Kaine of Virginia, was joined in Philadelphia on Monday by Obama, first lady Michelle Obama and Clinton's husband, former President Bill Clinton, along with singers Jon Bon Jovi and Bruce Springsteen. "We choose to believe in a hopeful, inclusive, big-hearted America," Clinton told a crowd of 33,000, the largest of her campaign.

(Additional reporting by Emily Stephenson and Amanda Becker traveling with the candidates, Doina Chiacu and Susan Heavey in Washington, Colleen Jenkins in Winston-Salem and Kim Palmer in Ohio; Writing by Alistair Bell; Editing by Will Dunham)